﻿#include "linux/types.h"
#include "drbd_wingenl.h"
#include "drbd_windows.h"

/* TODO: from which Linux source file was this taken? Which version? */

static u16 nla_attr_minlen[NLA_TYPE_MAX + 1] __read_mostly = {
    [NLA_U8] = sizeof(u8),
    [NLA_U16] = sizeof(u16),
    [NLA_U32] = sizeof(u32),
    [NLA_U64] = sizeof(u64),
    [NLA_NESTED] = NLA_HDRLEN,
};

static int validate_nla(struct nlattr *nla, int maxtype,
    const struct nla_policy *policy)
{
    const struct nla_policy *pt;
    int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);

    if (type <= 0 || type > maxtype)
        return 0;

    pt = &policy[type];

    BUG_ON(pt->type > NLA_TYPE_MAX);

    switch (pt->type)
    {
        case NLA_FLAG:
            if (attrlen > 0)
                return -ERANGE;
            break;

        case NLA_NUL_STRING:
            if (pt->len)
                minlen = min_t(int, attrlen, pt->len + 1);
            else
                minlen = attrlen;

            if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL)
                return -EINVAL;
            /* fall through */

        case NLA_STRING:
            if (attrlen < 1)
                return -ERANGE;

            if (pt->len)
            {
                char *buf = nla_data(nla);

                if (buf[attrlen - 1] == '\0')
                    attrlen--;

                if (attrlen > pt->len)
                    return -ERANGE;
            }
            break;

        case NLA_BINARY:
            if (pt->len && attrlen > pt->len)
                return -ERANGE;
            break;

        case NLA_NESTED_COMPAT:
            if (attrlen < pt->len)
                return -ERANGE;
            if (attrlen < NLA_ALIGN(pt->len))
                break;
            if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN)
                return -ERANGE;
			nla = (struct nlattr*)((int)nla_data(nla) + NLA_ALIGN(pt->len));
            if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN + nla_len(nla))
                return -ERANGE;
            break;
        default:
            if (pt->len)
                minlen = pt->len;
            else if (pt->type != NLA_UNSPEC)
                minlen = nla_attr_minlen[pt->type];

            if (attrlen < minlen)
                return -ERANGE;
    }

    return 0;
}

/**
* nla_validate - Validate a stream of attributes
* @head: head of attribute stream
* @len: length of attribute stream
* @maxtype: maximum attribute type to be expected
* @policy: validation policy
*
* Validates all attributes in the specified attribute stream against the
* specified policy. Attributes with a type exceeding maxtype will be
* ignored. See documenation of struct nla_policy for more details.
*
* Returns 0 on success or a negative error code.
*/
int nla_validate(struct nlattr *head, int len, int maxtype,
    const struct nla_policy *policy)
{
    struct nlattr *nla;
    int rem, err;

    nla_for_each_attr(nla, head, len, rem)
    {
        err = validate_nla(nla, maxtype, policy);
        if (err < 0)
            goto errout;
    }

    err = 0;
errout:
    return err;
}

/**
* nla_parse - Parse a stream of attributes into a tb buffer
* @tb: destination array with maxtype+1 elements
* @maxtype: maximum attribute type to be expected
* @head: head of attribute stream
* @len: length of attribute stream
*
* Parses a stream of attributes and stores a pointer to each attribute in
* the tb array accessable via the attribute type. Attributes with a type
* exceeding maxtype will be silently ignored for backwards compatibility
* reasons. policy may be set to NULL if no validation is required.
*
* Returns 0 on success or a negative error code.
*/
int nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head, int len,
    const struct nla_policy *policy)
{
    struct nlattr *nla;
    int rem, err;

    memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));

    nla_for_each_attr(nla, head, len, rem)
    {
        u16 type = nla_type(nla);

        if (type > 0 && type <= maxtype)
        {
            if (policy)
            {
                err = validate_nla(nla, maxtype, policy);
                if (err < 0)
                    goto errout;
            }

            tb[type] = nla;
        }
    }

    if (unlikely(rem > 0))
        printk(KERN_WARNING "netlink: %d bytes leftover after parsing "
        "attributes.\n", rem);

    err = 0;
errout:
    return err;
}

/**
* nla_find - Find a specific attribute in a stream of attributes
* @head: head of attribute stream
* @len: length of attribute stream
* @attrtype: type of attribute to look for
*
* Returns the first attribute in the stream matching the specified type.
*/
struct nlattr *nla_find(struct nlattr *head, int len, int attrtype)
{
    struct nlattr *nla;
    int rem;

    nla_for_each_attr(nla, head, len, rem)
        if (nla_type(nla) == attrtype)
            return nla;

    return NULL;
}

/**
* nla_strlcpy - Copy string attribute payload into a sized buffer
* @dst: where to copy the string to
* @src: attribute to copy the string from
* @dstsize: size of destination buffer
*
* Copies at most dstsize - 1 bytes into the destination buffer.
* The result is always a valid NUL-terminated string. Unlike
* strlcpy the destination buffer is always padded out.
*
* Returns the length of the source buffer.
*/
size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
{
    size_t srclen = nla_len(nla);
    char *src = nla_data(nla);

    if (srclen > 0 && src[srclen - 1] == '\0')
        srclen--;

    if (dstsize > 0)
    {
        size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;

        memset(dst, 0, dstsize);
        memcpy(dst, src, len);
    }

    return srclen;
}

/**
* nla_memcpy - Copy a netlink attribute into another memory area
* @dest: where to copy to memcpy
* @src: netlink attribute to copy from
* @count: size of the destination area
*
* Note: The number of bytes copied is limited by the length of
*       attribute's payload. memcpy
*
* Returns the number of bytes copied.
*/
int nla_memcpy(void *dest, const struct nlattr *src, int count)
{
    int minlen = min_t(int, count, nla_len(src));

    memcpy(dest, nla_data(src), minlen);

    return minlen;
}

/**
* nla_memcmp - Compare an attribute with sized memory area
* @nla: netlink attribute
* @data: memory area
* @size: size of memory area
*/
int nla_memcmp(const struct nlattr *nla, const void *data,
    size_t size)
{
    int d = nla_len(nla) - size;

    if (d == 0)
        d = memcmp(nla_data(nla), data, size);

    return d;
}

/**
* nla_strcmp - Compare a string attribute against a string
* @nla: netlink string attribute
* @str: another string
*/
int nla_strcmp(const struct nlattr *nla, const char *str)
{
    int len = strlen(str) + 1;
    int d = nla_len(nla) - len;

    if (d == 0)
        d = memcmp(nla_data(nla), str, len);

    return d;
}

/**
* __nla_reserve - reserve room for attribute on the skb
* @skb: socket buffer to reserve room on
* @attrtype: attribute type
* @attrlen: length of attribute payload
*
* Adds a netlink attribute header to a socket buffer and reserves
* room for the payload but does not copy it.
*
* The caller is responsible to ensure that the skb provides enough
* tailroom for the attribute header and payload.
*/
struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
{
    struct nlattr *nla;

    nla = (struct nlattr *) skb_put(skb, nla_total_size(attrlen));
    nla->nla_type = attrtype;
    nla->nla_len = nla_attr_size(attrlen);

    memset((unsigned char *)nla + nla->nla_len, 0, nla_padlen(attrlen));

    return nla;
}

/**
* __nla_reserve_nohdr - reserve room for attribute without header
* @skb: socket buffer to reserve room on
* @attrlen: length of attribute payload
*
* Reserves room for attribute payload without a header.
*
* The caller is responsible to ensure that the skb provides enough
* tailroom for the payload.
*/
void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
{
    void *start;

    start = skb_put(skb, NLA_ALIGN(attrlen));
    memset(start, 0, NLA_ALIGN(attrlen));

    return start;
}

/**
* nla_reserve - reserve room for attribute on the skb
* @skb: socket buffer to reserve room on
* @attrtype: attribute type
* @attrlen: length of attribute payload
*
* Adds a netlink attribute header to a socket buffer and reserves
* room for the payload but does not copy it.
*
* Returns NULL if the tailroom of the skb is insufficient to store
* the attribute header and payload.
*/
struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
{
    if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
        return NULL;

    return __nla_reserve(skb, attrtype, attrlen);
}

/**
* nla_reserve - reserve room for attribute without header
* @skb: socket buffer to reserve room on
* @len: length of attribute payload
*
* Reserves room for attribute payload without a header.
*
* Returns NULL if the tailroom of the skb is insufficient to store
* the attribute payload.
*/
void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
{
    if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
        return NULL;

    return __nla_reserve_nohdr(skb, attrlen);
}

/**
* __nla_put - Add a netlink attribute to a socket buffer
* @skb: socket buffer to add attribute to
* @attrtype: attribute type
* @attrlen: length of attribute payload
* @data: head of attribute payload
*
* The caller is responsible to ensure that the skb provides enough
* tailroom for the attribute header and payload.
*/
void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
    const void *data)
{
    struct nlattr *nla;

    nla = __nla_reserve(skb, attrtype, attrlen);
    memcpy(nla_data(nla), data, attrlen);
}

/**
* __nla_put_nohdr - Add a netlink attribute without header
* @skb: socket buffer to add attribute to
* @attrlen: length of attribute payload
* @data: head of attribute payload
*
* The caller is responsible to ensure that the skb provides enough
* tailroom for the attribute payload.
*/
void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
{
    void *start;

    start = __nla_reserve_nohdr(skb, attrlen);
    memcpy(start, data, attrlen);
}

/**
* nla_put - Add a netlink attribute to a socket buffer
* @skb: socket buffer to add attribute to
* @attrtype: attribute type
* @attrlen: length of attribute payload
* @data: head of attribute payload
*
* Returns -1 if the tailroom of the skb is insufficient to store
* the attribute header and payload.
*/
int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
{
    if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
        return -1;

    __nla_put(skb, attrtype, attrlen, data);
    return 0;
}

/**
* nla_put_nohdr - Add a netlink attribute without header
* @skb: socket buffer to add attribute to
* @attrlen: length of attribute payload
* @data: head of attribute payload
*
* Returns -1 if the tailroom of the skb is insufficient to store
* the attribute payload.
*/
int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
{
    if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
        return -1;

    __nla_put_nohdr(skb, attrlen, data);
    return 0;
}
